Preheat your oven to 400°F (200°C) and line a baking sheet with parchment paper.
In a large bowl, toss the broccoli florets, bell pepper strips, and sliced carrots with half of the avocado oil, half of the garlic powder, half of the onion powder, and a pinch of salt and pepper.
Spread the vegetables in a single layer on the prepared baking sheet and roast for 18-20 minutes until tender and slightly charred.
While the vegetables roast, season the chicken breast on both sides with the remaining garlic powder, onion powder, dried oregano, sea salt, and black pepper.
Heat the remaining avocado oil in a cast-iron or stainless steel skillet over medium-high heat.
Place the chicken in the hot skillet and sear for 5-7 minutes per side, or until the internal temperature reaches 165°F and the exterior is golden brown.
Remove the chicken from the pan and let it rest for 3 minutes before slicing.
Drizzle the roasted vegetables and chicken with fresh lemon juice before serving.